The correct option(s) related to the extraction of iron from its ore in the blast furnace operating in the temperature range \( 900 - 1500 \, \mathrm{K} \) is(are):
Limestone is used to remove silicate impurity.
Pig iron obtained from blast furnace contains about \( 4\% \) carbon.
Coke (\( \mathrm{C} \)) converts \( \mathrm{CO_2} \) to \( \mathrm{CO} \).
Exhaust gases consist of \( \mathrm{NO_2} \) and \( \mathrm{CO} \).
